Linux Overview

Like Unix, Linux can be generally divided into three major components: the kernel, the environment, and the file structure. The kernel is the core program that runs programs and manages hardware devices, such as disks and printers. The environment provides an interface for the user. It receives commands from the user and sends those commands to the kernel for execution. The file structure organizes the way files are stored on a storage device, such as a disk. Files are organized into directories. Each directory may contain any number of subdirectories, each holding files. Together, the kernel, the environment, and the file structure form the basic operating system structure. With these three, you can run programs, manage files, and interact with the system.

An environment provides an interface between the kernel and the user. It can be described as an interpreter. Such an interface interprets commands entered by the user and sends them to the kernel. Linux provides several kinds of environments: desktops, window managers, and command line shells. Each user on a Linux system has his or her own user interface. Users can tailor their environments to their own special needs, whether they be shells, window managers, or desktops. In this sense, for the user, the operating system functions more as an operating environment, which the user can control.

In Linux, files are organized into directories, much as they are in Windows. The entire Linux file system is one large interconnected set of directories, each containing files. Some directories are standard directories reserved for system use. You can create your own directories for your own files, as well as easily move files from one directory to another. You can even move entire directories, and share directories and files with other users on your system. With Linux, you can also set permissions on directories and files, allowing others to access them or restricting access to yourself alone. The directories of each user are, in fact, ultimately connected to the directories of other users. Directories are organized into a hierarchical tree structure, beginning with an initial root directory. All other directories are ultimately derived from this first root directory.

With the K Desktop Environment (KDE) and the GNU Network Object Model Environment (GNOME), Linux now has a completely integrated GUI interface. You can perform all your Linux operations entirely from either interface. KDE and GNOME are fully operational desktops supporting drag-and-drop operations, enabling you to drag icons to your desktop and to set up your own menus on an Applications panel. Both rely on an underlying X Window System, which means as long as they are both installed on your system, applications from one can run on the other desktop. The GNOME and KDE sites are particularly helpful for documentation, news, and software you can download for those desktops. Both desktops can run any X Window System program, as well as any cursor-based program such as Emacs and Vi, which were designed to work in a shell environment. At the same time, a great many applications are written just for those desktops and included with your distributions. The K Desktop has a complete set of Internet tools, along with editors and graphic, multimedia, and system applications. GNOME has slightly fewer applications, but a great many are currently in the works. Check their Web sites at www.gnome.org and www.kde.org for new applications. As new versions are released, they include new software.

Note

Ximian currently maintains an enhanced version of GNOME called Ximian Desktop at www.ximian.com.